CRAN Mirror HOWTO/FAQ

This page explains how to create a new CRAN mirror,
which is fairly simple. If you would like to become an official CRAN
mirror, please be sure to read and follow these instructions
carefully. You should have the consent of your hosting company (if you
aren't a hosting company yourself), and be prepared for some
reasonably significant bandwidth usage. The full size of CRAN was
approx 120GB on 2012-10-16 (and we are growing all the time).

We currently have no written set of rules when we accept a new mirror
into the official list. PHP accepts only up to two mirrors per country, we
think there may be need to treat China different from, say,
Luxembourg. So use common sense and ask yourself whether your mirror
helps the R community. We want good global coverage, but also short
lists on the mirror webpage or in a GUI. In
addition, human time is involved in maintaining the list and monitoring it. If there is no mirror in
your country, it will usually accepted. Otherwise ask first if in
doubt.

Where do I get a copy of CRAN?

All you have to do is recursively mirror the complete tree to your
webserver on a regular basis (at least twice a week, better every 1-2
days, but not more than twice a day). Which software you use for mirroring depends on the operating
system of your server, but we strongly recommend that you use rsync.
For security reasons we furthermore recommend mirroring over a SSH tunnel.
You may want to call rsync using the following arguments:

Please send your public SSH key to cran-sysadmin@r-project.org in advance and
do not forget the --delete flag to remove files from the mirror that are no longer present on the master.

The CRAN tree uses symbolic links, and so rysnc may not work as expected to a Windows server.

It may be necessary to replace-l by -L in the above (and this will also be necessary for some partial mirrors, e.g., those excluding the contrib/Archive area).

Server configuration

CRAN contains no dynamic pages, so no special configuration of your
web server is needed. The only exception is that files with extension
.shtml need to be recognised as HTML pages, but that is the
default for most server software anyway. The main frame of the CRAN
top page banner.shtml has this extension, so you will
immediately see it in case something is wrong.

If you use the Apache web server and want to promote the hosting
institution of the mirror you may want to add something like

SetEnv CRAN_HOST "This server is hosted by bla bla bla ..."

to your Apache configuration. The string "This server ..."
(which may contain
HTML markup) will be added in the footer of the CRAN top page, see the
main server for
an example. You also need something like

in the MIME-types section of the Apache configuration, the exact
syntax depends on the version of Apache. All you have to do
is uncomment these (or similar) lines in the default configuration.

Furthermore, it is necessary that your web server is configured to
allow redirections. You need this to enable redirection to package
web pages. E.g.,

http://cran.r-project.org/package=foo

redirects to

http://cran.r-project.org/web/packages/foo/index.html

The same also is possible for task views:

http://cran.r-project.org/view=bar

If you use the Apache web server this feature can be enabled by
loading the mod_rewrite module. A .htaccess file (typically
synced with the CRAN mirror) in CRAN's
root directory does the rest of the configuration. If this last step
fails for some reason (e.g., you do not allow .htaccess files, which is the default since Apache 2.4) then
you have to add the following lines to your Apache
configuration:

Apache version 2.4 and newer does not recognise the syntax
used in banner.shtml and allow the use of .htaccess files by
default.
The previously mentioned .htaccess file also enables the
syntax in banner.shtml to be recognised and in order to use it, change
your Apache Configuration to:

AllowOverride All

If this last step fails, or you do not want to
allow .htaccess files, then you have to add the following
line to your Apache configuration, similar to the Rewrite Rules:

SSILegacyExprParser on

Inform us!

Once your mirror is up and running and the automatic updates work for
a couple of days send email to
cran@r-project.org such that we
can include your site in the list of mirrors. Please include the
following information in your email: